Abstract: A filter apparatus consists of a combination of various filter elements combined to form a structural unit, one filter element of these filter elements serving to clean of particles and another filter element to clean oil oxidation products from a fluid stream, the filter elements being mounted in parallel to each other for the respective cleaning of the fluid stream.

Abstract: The invention relates to a filter device, comprising a filter housing (10), which has an inlet (12) for unfiltered medium and an outlet (14) for filtered medium and which accommodates an exchangeable filter element (16). When unfiltered medium flows through said filter element from the outside in, it flows through both a hollow cylindrical element material (18) and an element material (22) which closes the hollow cylinder (18) at one free end (20) of the hollow cylinder. At the other free end (24) of the hollow cylinder, an element cap (26) having a central opening (28) is used to discharge filtered medium to the outlet (14) in the filter housing (10), the outlet being connected to the central opening (28). Each element material (18, 22) is accommodated seal-free in the filter housing (10) for incident flow on all sides, from the outside in.

Abstract: A method adapts a filter medium to predefinable parameters, such as electrostatic charge, flow-rate behavior, dynamic pressure behavior or differential pressure behavior, fraction filtration efficiency and preservation of a constant quantity and quality of fluid additives. At least one of these parameters is adapted by the targeted influencing of the surface energy of the filter medium (18).

Abstract: A filter element (1), with a preferably multilayer structure of a filter medium (3), in pleated form has filter pleats (5, 7) of different pleat heights (h1, h2). The filter pleats (7) with a first pleat height (h1) oppose the filter pleats (5) lower second pleat height (h2). The filter element has a throughflow direction for fluid to be cleaned away from a dirty side to a clean side (R). The transitions arranged adjacent to the inner side all conclude along a fictitious circular cylinder (9), which penetrates the filter medium (3) coaxially to its longitudinal axis (LA).

Abstract: The invention relates to a method for adapting a filter medium to predefinable parameters, such as electrostatic charge, flow-rate behaviour, dynamic pressure behaviour or differential pressure behaviour, fraction filtration efficiency and preservation of a constant quantity and quality of fluid additives. Said method is characterised in that at least one of the aforementioned parameters is adapted by the targeted influencing of the surface energy of the filter medium (18).

Abstract: A filter element (1), with a preferably multilayer structure of a fiber medium (3) that has, in pleated form, filter pleats (5, 7) of different pleat heights (h1, h2), with filter pleats (7) with a first pleat height (h1) and with filter pleats (5) with an opposing lower second pleat height (h2), wherein the filter element has a throughflow direction for fluid to be cleaned away from a dirty side to a clean side (R), is characterized in that the transitions arranged adjacent to the clean side (R) or the dirty side (S) all conclude along a fictitious circular cylinder (9), which penetrates the filter medium (3) coaxially to its longitudinal axis (LA).